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94 Cards in this Set

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What is the term for molten rock material below ground?
Magma
What is the term for molten rock aboveground?
Lava
What is the term for igneous rocks that form above ground?
Volcanic
What is the term for igneous rocks that form below ground?
Plutonic
What is the term for the measure of a liquid's resistance to flow?
Viscosity
What is the general term for igneous landform that forms underground?
Pluton
What is the term for the increase in Earth's temperature with depth?
Geothermal Gradient
What is the term for the size, shape and arrangement of mineral grains?
Texture
What is the term for magma with over 65% silica?
Felsic
What is the term for magma with 45-52% silica?
Mafic
What is the term magma with around 52-65% silica?
Intermediate
What is the term for texture where minerals are too small to see?
Aphanitic
What is the term for texture where minerals are clearly visible?
Phaneritic
What is the term for texture with mix of mineral sizes, some clearly visible?
Porphyritic
How long does it take for Plutons to cool off?
1,000's-1,000,000's years to cool off

thousands to millions of years to cool off.
Why does it take Plutons thousands to millions of years to cool off?
Rocks are poor conductors of heat.
Does water increase or decrease the temperature needed to melt rocks?
Water DECREASES the temperature needed to melt rocks.
Why does water decrease the temperature needed to melt rocks?
Water helps to break chemical bonds in minerals.
Do Aphanitic igneous textures generally indicate cooling above or below ground?
Aphanitic igneous textures generally indicate cooling ABOVE ground
Are there exceptions to Aphanitic igneous textures indicating cooling above ground?
Yes, aphanitic igneous textures may form in shallow intrusions.
What is the term for the type of texture that large amounts of water vapor and other gases in lava cause it to have?
Vesicular Texture
Andesite is formed from what kind of magmas?
Andesite is formed from magmas of INTERMEDIATE composition.
What is Andesite mostly composed of?
Phagioclase
Where does Andesite form?
Andesite forms at CONVERGENT margins.
Where do Felsic magmas cool?
Felsic magmas cool within the CONTINENTAL crust.
Do Felsic magmas cool rapidly or slowly?
Felsic magmas cool slowly.
What do Felsic magmas cool slowly into?
Felsic magmas cool slowly to form GRANITE.
What kind of texture does Granite have?
Phaneritic
Name the 3 main minerals found in Granite:
1. Quartz
2. Potassium Feldspar
3. Plagioclase
Name the 2 important elements that are found in Complex Pegmatites:
1. Lithium
2. Cesium
Name 3 minerals found in Complex Pegmatites:
1. Rubidium
2. Beryllium
3. Tin
4. Muscovite
Name 3 gems found in Complex Pegmatites:
1. Feldspar
2. Spodumene
3. Tourmaline
Generally, what kind of Plutons are Batholiths?
Batholiths are generally COMPOSITE plutons
How are Batholiths generally formed?
Batholiths are formed by multiple intrusions of FELSIC or GRANITE magma
Where are Batholiths generally formed?
Batholiths are formed along CONVERGENT BOUNDARIES.
Where do Ferromagnesium minerals form?
Ferromagnesium minerals form on the DISCONTINUANCE SEQUENCE of Bowen's series
What are the 2 types of magmas that Ferromagneium minerals most in common with?
1. Ultramafic magma
2. Mafic magma
What are the 2 features that are the basis for most igneous rocks classification.
1. Composition
2. Texture
Which of the following minerals is NOT found on Bowen's series?
1. quartz
2. olivine
3. plagioclase
4. calcite
5. biotite
4. Calcite
Why do phaneritic igneous textures form?
Because phanertic igneous textures cool slowly.
Why are quartz and potassium feldspar typically found in the same igneous rock?
Because both quartz and potassium feldspar form at similar temperatures.
How are igneous rocks named?
Igneous rocks are named based on:
1. composition
2. texture
Why is Bowen's series useful?
Bowen's series is useful because it EXPLAINS MINERAL ASSOCIATIONS IN IGNEOUS ROCKS.
Name the 3 different textures that igneous rocks that cool rapidly may develop:
1. aphanitic
2. vesicular
3. pyroclastic
Name 4 types of igneous rocks that cool slowly?
1. gabbro
2. peridotite
3. granite
4. diorite
T or F
Igneous rocks that cool slowly include obsidian.
FALSE,
Igneous rocks that cool slowly do NOT include obsidian
T or F
Mafic lava temperatures can exceed 1000 degress Celsius
TRUE
T or F
Mafic lava behaves as a liquid.
TRUE
T or F
Mafic lava has a relatively low viscosity.
TRUE
T or F
Mafic lava is generally less explosive.
TRUE
What mainly controls the viscosity in magmas and lavas?
Silica content
Why is Felsic Lava less common that Mafic lava?
Felsic magma is more viscous.
Where does magma form?
Magma form in the:
1. Upper Mantle
2. Lower crust
T or F
The last minerals to form according to Bowen's series are low in iron and magnesium.
TRUE
Why are the last minerals to form according to Bowen's series low in iron and magnesium?
Because Iron and Magnesium were used up to form Ferromagnesium minerals.
Remeber: Ferro means iron.
Magma can be created at spreading ridges by what 2 physical influences?
1. Earth's natural heat
2. DECREASE in pressure
List the 4 influences that control the composition of an igneous rock:
1. A parent magma composition
2. Crystal settling
3. Assimilation and magma mixing
4. Mineral crystallization sequence
What is the main difference between Gabbro and Basalt?
Gabbro has more quartz.
T or F
Sills are typically shallow intrusions.
TRUE
T or F
Sills are usually intruded into sedimentary rocks.
TRUE
T or F
Sills are tabular and concordant plutons.
TRUE
T or F
Sills are probably responsible for some increase in volcano size before eruptions.
TRUE
What is the term for concordant, mushroom shaped plutons?
Laccoliths
Name the 4 ways large Batholiths can form and move?
1. Granitization in place
2. Stoping
3. Displacing and trading places with the rocks above.
4. Assimilation
What is the source for the largest plutons?
Felsic magmas
What is the term for the largest plutons?
Batholiths
T or F
Most magma never reaches the surface.
TRUE
T or F
Most magma is rich in carbonate.
FALSE
T or F
Most magma forms pyroclastic matter.
FALSE
T or F
Most magma contains at least 10% water.
FALSE
What are the 4 reason for a volcano erupting lava of different compositions?
1. Magma mixing
2. Assimilation
3. Crystal settling
4. Mineral crystallization sequence.
What is the term for fragments erupted out of a volcano that fall through the air?
Pryoclastic material
T or F
Erupting lava temperatures are at least 9X that of boiling water.
TRUE
T or F
Erupting lava temperatures are impossible to measure.
FALSE
T or F
Erupting lava temperatures are cool enough for forest service trucks to safely drive over.
FALSE
T or F
Erupting lava temperatures are typically hotter than magma termperatures.
FALSE
T or F
Erupting lava temperatures are cooled extremely quickly by exposure to air.
FALSE
What source is Potassium Feldspar most likely to form in?
Granite
What happens to the shape of minerals in the discontinuous branch of Bowen's series with decreasing temperatures?
With decreasing temperatures, minerals in the the discontinuous branch of Bowen's series change from ISOLATED TETRAHEDRA TO SHEET SILICATES.
What are the 4 influences that the act of Melting depends on:?
1. Composition
2. Temperature
3. Pressure
4. Amount of Water
Why does Partial Melting occur?
Partial melting occurs because different minerals melt at different temperatures.
What are the 3 reasons why Phaneritic Texture forms?
1. Crystal growth rate exceeds nuclei formation rate
2. The magma cools slowly
3. The magma cools underground
What is the term for larger mineral crystals in a porphyry?
Phenocrysts.
T or F
Mount Rushmore is carved into Gabbro.
FALSE
T or F
Any magma is less dense than the rock it came from.
TRUE
T or F
Igneous rocks are mostly made of silicate minerals.
TRUE
T or F
Felsic lavas are viscous because silica tetrahedra slow and thicken the lava.
TRUE
T or F
Magma chambers are only found under convergent boundaries.
FALSE
T or F
The temperature at which rocks melt rises with increasing pressure.
TRUE
T or F
A single volcano will always erupt lava of identical composition since it all comes from the same magma chamber.
FALSE
T or F
Mineral grain size in an igneous rock records cooling history.
TRUE
T or F
Porphyry is an igneous rock that cooled at first slowly and then rapidly.
TRUE
T or F
Granite rocks are the primary source of god.
TRUE
T or F
Laccoliths and BAtholiths are usually felsic.
TRUE